That

Seven “thats” may follow each other, and make sense.

For be it known that we may safely write
Or say that `that that' that that man wrote was right;
Nay, e'en that that that, that `that THAT' has followed,
Through six repeats, the grammar's rule has hallowed;
And that that that that that `that THAT' began
Repeated seven times is right, deny't who can.

“My lords, with humble submission that that I say is this:
That that that `that that' that that gentleman has advanced is not
that that he should have proved to your lordships.” —Spectator, No. 86.